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Charge control agent, toner using same developer containing the toner and developing device containing the developer

a technology of charge control agent and developer, which is applied in the direction of electrographic process, instruments, transportation and packaging, etc., can solve the problems of chromium and zinc environmental problems, safety problems against human bodies, and one or more defects of known charge control agents, etc., to maintain the charging amount and stable manner

Inactive Publication Date: 2005-12-20
RICOH KK +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0012]It is, therefore, an object of the present invention to provide a charge control agent which, when incorporated into toner particles, can exhibit triboelectricity suitable for a given image developing system upon frictional contact between toner particles, between toner and carrier, between toner and a developer bearing member (such as a developer sleeve) and between toner and a thickness regulating member (such as a blade) and which can maintain the charging amount in a stable manner.
[0013]Another object of the present invention is to provide a charge control agent of the above-mentioned type which can afford suitable charging amount in a moment irrespective of presence or absence of a releasing agent and of difference is the developing system.
[0014]It is a further object of the present invention to provide a charge control agent which can be suitably used for both one-component type and two-component type developers.

Problems solved by technology

The known charge controlling agents, however, suffer from one or more defects such as non-uniformity in triboelectricity and susceptibility to decomposition during kneading.
Further, the use of a charge control agent containing heavy metals such as chromium, nickel, chromium and zinc has environmental problems and safety problems against human bodies.
These charge control agents are, however, hygroscopic in nature and are apt to cause a change in their triboelectricity.
Additionally, they do not have highly satisfactory triboelectricity.
When these binder resins are used in conjunction with the above known charge control agents, sufficiently high triboelectricity cannot be obtained or the triboelectricity gradually reduces even when the initial triboelectricity is high, so that problems of fatigue or toner dispersion are apt to be caused.
Probably, the problems are attributed to the presence of —COOH and —OH functional groups in these resins which groups would prevent maintenance of stable triboelectricity of the charge control agents.
The use of the oil requires the installation of an oil tank and hinders compactness of the apparatus.
The use of wax, however, reduces the fluidity of the toner particles and, hence, it becomes difficult to obtain desired amount of charge in a moment by friction.
Currently available white or colorless charge control agents, however, do not have good charging characteristics or are very expensive.

Method used

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  • Charge control agent, toner using same developer containing the toner and developing device containing the developer
  • Charge control agent, toner using same developer containing the toner and developing device containing the developer
  • Charge control agent, toner using same developer containing the toner and developing device containing the developer

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0078]

Preparation of developer:Styrene-methyl acrylate copolymer resin100partsCarbon black10partsPalmitic acid calcium salt1.5parts

[0079]The above ingredients were thoroughly mixed with a Henschel mixer and the mixture was kneaded with a roll mill at 130 to 140° C. for about 30 minutes. The kneaded mixture was solidified by cooling to room temperature and the solid mass was grounded and sieved to obtain base toner particles having a volume average particle diameter of 8.0±0.5 μm. 100 Parts of the base toner particles were mixed with 0.5 part of hydrophobic silica and 0.2 part of titanium oxide as external additives to obtain a toner. The toner (2.5 parts) was mixed with 97.5 parts of iron carrier having a particle size of 100 to 250 mesh using a Turbler mixer to obtain a developer.

Evaluation:

[0080]The developer obtained above was charged in a copying machine, IMAGIO MF530, manufactured by Ricoh Company, Ltd. and images were reproduced at room temperature environment. Uniform images ...

example 2

[0087]

Preparation of developer:Styrene-butyl acrylate copolymer resin100partsCarbon black10partsMonohydroxymonocarboxynaphthalene-2.5partsmonosulfonic acid calcium salt

[0088]Using the above ingredients, a toner was prepared in the same manner as described in Example 1. The toner thus obtained had a volume average particle diameter of 8.0±0.5 μm. A developer was then prepared in the same manner as described in Example 1.

Evaluation:

[0089]The developer obtained above was tested in the same manner as that in Example 1 except that a copying machine (manufactured by Ricoh Company, Ltd.) of an oil application type was used. The initial charge amount was −21 μC / g. Uniform images having a high image density and free of background stains were obtained in the initial copying stage. No image defects were detected even after production of 50,000 copies. The charge amount after production of 50,000 copies was −18 μC / g. Good images were found to be obtained in the low temperature and low relative ...

example 3

[0090]

Preparation of developer:Styrene-butyl acrylate copolymer resin100partsCarbon black10partsBenzenesulfonic acid calcium salt2.5parts

[0091]Using the above ingredients, a toner was prepared in the same manner as described in Example 1. The toner thus obtained had a volume average particle diameter of 8.0±0.5 μm. A developer was then prepared in the same manner as described in Example 1.

Evaluation:

[0092]The developer obtained above was tested in the same manner as that in Example 1 except that a copying machine (manufactured by Ricoh Company, Ltd.) of an oil application type was used. The initial charge amount was −21 μC / g. Uniform images having a high image density and free of background stains were obtained in the initial copying stage. No image defects were detected even after production of 50,000 copies. The charge amount after production of 50,000 copies was −22 μC / g. Good images were found to be obtained in the low temperature and low relative humidity environment and in the...

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Abstract

A charge control agent containing a calcium salt of a sulfoisophthalic acid compound. A toner for developing an electrostatic latent image including the above charge control agent, a binder resin and a colorant.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]This invention relates to a charge control agent useful for controlling triboelectricity of a toner for developing an electrostatic latent image. The present invention is also directed to a toner for use in developing an electrostatic latent image in an image forming method such as electrophotography, electrostatic recording and electrostatic printing and to a developing device using the developer.[0003]2. Description of the Prior Art[0004]Methods for developing an electrostatic latent image to form a toner image include a method using a one-component type developer composed only of a toner and a method using a two-component type developer composed of a toner and a carrier which are charged in opposite polarity. The one-component type method may be, for example, a powder cloud developing method in which toner particles are sprayed over an electrostatic latent image-bearing surface, a contact developing method (touch dow...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): G03G9/087G03G9/10G03G9/09G03G9/097
CPCG03G9/0975G03G9/09783Y10T428/2913
Inventor SAITO, TAKUYASUZUKI, MASANORIWATANABE, YOHICHIROHSHIRAISHI, KEIKOSAWADA, TOYOSHIOSAKI, TATSUHIKOARATANI, SATOSHIOGISO, HIROKI
Owner RICOH KK